#include "rar.hpp"

RarVM::RarVM()

{

  Mem=NULL;

}

RarVM::~RarVM()

{

  delete[] Mem;

}

void RarVM::Init()

{

  if (Mem==NULL)

    Mem=new byte[VM_MEMSIZE+4];

}

void RarVM::Execute(VM_PreparedProgram *Prg)

{

  memcpy(R,Prg->InitR,sizeof(Prg->InitR));

  Prg->FilteredData=NULL;

  if (Prg->Type!=VMSF_NONE)

  {

    bool Success=ExecuteStandardFilter(Prg->Type);

    uint BlockSize=Prg->InitR[4] & VM_MEMMASK;

    Prg->FilteredDataSize=BlockSize;

    if (Prg->Type==VMSF_DELTA || Prg->Type==VMSF_RGB || Prg->Type==VMSF_AUDIO)

      Prg->FilteredData=2*BlockSize>VM_MEMSIZE || !Success ? Mem:Mem+BlockSize;

    else

      Prg->FilteredData=Mem;

  }

}

void RarVM::Prepare(byte *Code,uint CodeSize,VM_PreparedProgram *Prg)

{

  // Calculate the single byte XOR checksum to check validity of VM code.

  byte XorSum=0;

  for (uint I=1;I<CodeSize;I++)

    XorSum^=Code[I];

  if (XorSum!=Code[0])

    return;

  struct StandardFilters

  {

    uint Length;

    uint CRC;

    VM_StandardFilters Type;

  } static StdList[]={

    53, 0xad576887, VMSF_E8,

    57, 0x3cd7e57e, VMSF_E8E9,

   120, 0x3769893f, VMSF_ITANIUM,

    29, 0x0e06077d, VMSF_DELTA,

   149, 0x1c2c5dc8, VMSF_RGB,

   216, 0xbc85e701, VMSF_AUDIO

  };

  uint CodeCRC=CRC32(0xffffffff,Code,CodeSize)^0xffffffff;

  for (uint I=0;I<ASIZE(StdList);I++)

    if (StdList[I].CRC==CodeCRC && StdList[I].Length==CodeSize)

    {

      Prg->Type=StdList[I].Type;

      break;

    }

}

uint RarVM::ReadData(BitInput &Inp)

{

  uint Data=Inp.fgetbits();

  switch(Data&0xc000)

  {

    case 0:

      Inp.faddbits(6);

      return (Data>>10)&0xf;

    case 0x4000:

      if ((Data&0x3c00)==0)

      {

        Data=0xffffff00|((Data>>2)&0xff);

        Inp.faddbits(14);

      }

      else

      {

        Data=(Data>>6)&0xff;

        Inp.faddbits(10);

      }

      return Data;

    case 0x8000:

      Inp.faddbits(2);

      Data=Inp.fgetbits();

      Inp.faddbits(16);

      return Data;

    default:

      Inp.faddbits(2);

      Data=(Inp.fgetbits()<<16);

      Inp.faddbits(16);

      Data|=Inp.fgetbits();

      Inp.faddbits(16);

      return Data;

  }

}

void RarVM::SetMemory(size_t Pos,byte *Data,size_t DataSize)

{

  if (Pos<VM_MEMSIZE && Data!=Mem+Pos)

  {

    // We can have NULL Data for invalid filters with DataSize==0. While most

    // sensible memmove implementations do not care about data if size is 0,

    // let's follow the standard and check the size first.

    size_t CopySize=Min(DataSize,VM_MEMSIZE-Pos);

    if (CopySize!=0)

      memmove(Mem+Pos,Data,CopySize);

  }

}

bool RarVM::ExecuteStandardFilter(VM_StandardFilters FilterType)

{

  switch(FilterType)

  {

    case VMSF_E8:

    case VMSF_E8E9:

      {

        byte *Data=Mem;

        uint DataSize=R[4],FileOffset=R[6];

        if (DataSize>VM_MEMSIZE || DataSize<4)

          return false;

        const uint FileSize=0x1000000;

        byte CmpByte2=FilterType==VMSF_E8E9 ? 0xe9:0xe8;

        for (uint CurPos=0;CurPos<DataSize-4;)

        {

          byte CurByte=*(Data++);

          CurPos++;

          if (CurByte==0xe8 || CurByte==CmpByte2)

          {

            uint Offset=CurPos+FileOffset;

            uint Addr=RawGet4(Data);

            // We check 0x80000000 bit instead of '< 0' comparison

            // not assuming int32 presence or uint size and endianness.

            if ((Addr & 0x80000000)!=0)              // Addr<0

            {

              if (((Addr+Offset) & 0x80000000)==0)   // Addr+Offset>=0

                RawPut4(Addr+FileSize,Data);

            }

            else

              if (((Addr-FileSize) & 0x80000000)!=0) // Addr<FileSize

                RawPut4(Addr-Offset,Data);

            Data+=4;

            CurPos+=4;

          }

        }

      }

      break;

    case VMSF_ITANIUM:

      {

        byte *Data=Mem;

        uint DataSize=R[4],FileOffset=R[6];

        if (DataSize>VM_MEMSIZE || DataSize<21)

          return false;

        uint CurPos=0;

        FileOffset>>=4;

        while (CurPos<DataSize-21)

        {

          int Byte=(Data[0]&0x1f)-0x10;

          if (Byte>=0)

          {

            static byte Masks[16]={4,4,6,6,0,0,7,7,4,4,0,0,4,4,0,0};

            byte CmdMask=Masks[Byte];

            if (CmdMask!=0)

              for (uint I=0;I<=2;I++)

                if (CmdMask & (1<<I))

                {

                  uint StartPos=I*41+5;

                  uint OpType=FilterItanium_GetBits(Data,StartPos+37,4);

                  if (OpType==5)

                  {

                    uint Offset=FilterItanium_GetBits(Data,StartPos+13,20);

                    FilterItanium_SetBits(Data,(Offset-FileOffset)&0xfffff,StartPos+13,20);

                  }

                }

          }

          Data+=16;

          CurPos+=16;

          FileOffset++;

        }

      }

      break;

    case VMSF_DELTA:

      {

        uint DataSize=R[4],Channels=R[0],SrcPos=0,Border=DataSize*2;

        if (DataSize>VM_MEMSIZE/2 || Channels>MAX3_UNPACK_CHANNELS || Channels==0)

          return false;

        // Bytes from same channels are grouped to continual data blocks,

        // so we need to place them back to their interleaving positions.

        for (uint CurChannel=0;CurChannel<Channels;CurChannel++)

        {

          byte PrevByte=0;

          for (uint DestPos=DataSize+CurChannel;DestPos<Border;DestPos+=Channels)

            Mem[DestPos]=(PrevByte-=Mem[SrcPos++]);

        }

      }

      break;

    case VMSF_RGB:

      {

        uint DataSize=R[4],Width=R[0]-3,PosR=R[1];

        if (DataSize>VM_MEMSIZE/2 || DataSize<3 || Width>DataSize || PosR>2)

          return false;

        byte *SrcData=Mem,*DestData=SrcData+DataSize;

        const uint Channels=3;

        for (uint CurChannel=0;CurChannel<Channels;CurChannel++)

        {

          uint PrevByte=0;

          for (uint I=CurChannel;I<DataSize;I+=Channels)

          {

            uint Predicted;

            if (I>=Width+3)

            {

              byte *UpperData=DestData+I-Width;

              uint UpperByte=*UpperData;

              uint UpperLeftByte=*(UpperData-3);

              Predicted=PrevByte+UpperByte-UpperLeftByte;

              int pa=abs((int)(Predicted-PrevByte));

              int pb=abs((int)(Predicted-UpperByte));

              int pc=abs((int)(Predicted-UpperLeftByte));

              if (pa<=pb && pa<=pc)

                Predicted=PrevByte;

              else

                if (pb<=pc)

                  Predicted=UpperByte;

                else

                  Predicted=UpperLeftByte;

            }

            else

              Predicted=PrevByte;

            PrevByte=DestData[I]=(byte)(Predicted-*(SrcData++));

          }

        }

        for (uint I=PosR,Border=DataSize-2;I<Border;I+=3)

        {

          byte G=DestData[I+1];

          DestData[I]+=G;

          DestData[I+2]+=G;

        }

      }

      break;

    case VMSF_AUDIO:

      {

        uint DataSize=R[4],Channels=R[0];

        byte *SrcData=Mem,*DestData=SrcData+DataSize;

        // In fact, audio channels never exceed 4.

        if (DataSize>VM_MEMSIZE/2 || Channels>128 || Channels==0)

          return false;

        for (uint CurChannel=0;CurChannel<Channels;CurChannel++)

        {

          uint PrevByte=0,PrevDelta=0,Dif[7];

          int D1=0,D2=0,D3;

          int K1=0,K2=0,K3=0;

          memset(Dif,0,sizeof(Dif));

          for (uint I=CurChannel,ByteCount=0;I<DataSize;I+=Channels,ByteCount++)

          {

            D3=D2;

            D2=PrevDelta-D1;

            D1=PrevDelta;

            uint Predicted=8*PrevByte+K1*D1+K2*D2+K3*D3;

            Predicted=(Predicted>>3) & 0xff;

            uint CurByte=*(SrcData++);

            Predicted-=CurByte;

            DestData[I]=Predicted;

            PrevDelta=(signed char)(Predicted-PrevByte);

            PrevByte=Predicted;

            int D=(signed char)CurByte;

            // Left shift of negative value is undefined behavior in C++,

            // so we cast it to unsigned to follow the standard.

            D=(uint)D<<3;

            Dif[0]+=abs(D);

            Dif[1]+=abs(D-D1);

            Dif[2]+=abs(D+D1);

            Dif[3]+=abs(D-D2);

            Dif[4]+=abs(D+D2);

            Dif[5]+=abs(D-D3);

            Dif[6]+=abs(D+D3);

            if ((ByteCount & 0x1f)==0)

            {

              uint MinDif=Dif[0],NumMinDif=0;

              Dif[0]=0;

              for (uint J=1;J<ASIZE(Dif);J++)

              {

                if (Dif[J]<MinDif)

                {

                  MinDif=Dif[J];

                  NumMinDif=J;

                }

                Dif[J]=0;

              }

              switch(NumMinDif)

              {

                case 1: if (K1>=-16) K1--; break;

                case 2: if (K1 < 16) K1++; break;

                case 3: if (K2>=-16) K2--; break;

                case 4: if (K2 < 16) K2++; break;

                case 5: if (K3>=-16) K3--; break;

                case 6: if (K3 < 16) K3++; break;

              }

            }

          }

        }

      }

      break;

  }

  return true;

}

uint RarVM::FilterItanium_GetBits(byte *Data,uint BitPos,uint BitCount)

{

  uint InAddr=BitPos/8;

  uint InBit=BitPos&7;

  uint BitField=(uint)Data[InAddr++];

  BitField|=(uint)Data[InAddr++] << 8;

  BitField|=(uint)Data[InAddr++] << 16;

  BitField|=(uint)Data[InAddr] << 24;

  BitField >>= InBit;

  return BitField & (0xffffffff>>(32-BitCount));

}

void RarVM::FilterItanium_SetBits(byte *Data,uint BitField,uint BitPos,uint BitCount)

{

  uint InAddr=BitPos/8;

  uint InBit=BitPos&7;

  uint AndMask=0xffffffff>>(32-BitCount);

  AndMask=~(AndMask<<InBit);

  BitField<<=InBit;

  for (uint I=0;I<4;I++)

  {

    Data[InAddr+I]&=AndMask;

    Data[InAddr+I]|=BitField;

    AndMask=(AndMask>>8)|0xff000000;

    BitField>>=8;

  }

}